Chables e



- CHARLES SORIBNEB, on CHICAGO, ILLINOIS, AssIeNoR Torr-IE WESTERN UNITE STATES ELECTRIC COMPANY, OF SAME PLACE.

TRANSFER SWITCH AND ,C IRCUIT FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming part of Letters Patent No. 377,441, dated-February 7, 1888. f

Application filed July 11. recs.

To all whom it may concern:

Be it known that 1, CHARLES E. ScRIBNER, a citizen of the UnitedStates, residing at Ohicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Transfer Switches and Cir fcuits for Telephone-Exchanges, (Case 80), of

j I avoid leaving the lines open by using springwhich the following is a full, clear, concise, and exact description, referencebeing had to the accompanying drawings, forming a part of this specification.

My invention relates to telephone-exchanges in which the telephone-lines are grouped upon different tables or switch-boards. V

The object of my invention is to afford facilities for making connections over the trunk lines between the different boards without the liability of leaving any subscribers line open, or 1n such condition that the subscriber cannot signal the central-office. I

Heretofore simple thimbles or sockets have been used as the terminals for the trunk lines on the different boards, and the failure of either switchman to disconnect his subscribers line from the transfer or trunk line leaves the line open, and the subscriber whose line is jack switches as terminals for the transferwires, and circuits by means of which the grounds are removed when two lines are connected together. through any given transferline, the groundconnection of the transferline, however, being reestablished when either of the telephones is disconnected therefrom. In the drawings,'Figure 1, Ihave shown three standard switch-boards, A B C. To each of these boards fifty telephone-lines may be connected in the usual manner. Fig. 2 is a diagram illustrative of a single transfer-Wire cir- Serial No. 171,368. (No model.)

cuit. Fig. 3 is a detailed sectional view'ofthe ordinary Warnerspring-jack, which I use both may beplaced, as shown, in the frames outside of the portion of the board which con tains the telephone-line springjack.

Referring now to Fig. '2, itwill be seen that 'PATENTI OFFICE-Q LY when plugs are inserted in spring-jacks a c said plugs will be connected together, while the ground-connections at c of said springjacks willbe takenoff, as shown. The circuit between said plugs maybe traced-from the point of the plug inserted in spring-jacket,

through spring-jacka, thencethrough springa jack b, and thence to spring-jack c, and to the" point of the plug inserted therein, as shown. Thus line 38 of board A may be connected with line'133 of board 0 by means of a pain;

of cords at each board and the transfer-wire connection. 1

For clearness I have omittedffrom'boards 7.5

and G the greater portion of; the shutters and spring-jacks, and'haveillustrated the transfer-circuitbetween terminals a a 12b 0 c in a t separate figure-that is to say, in Fig. 2.

Suppose the switchman at board A forgets; to disconnect line 38 when line 133 has been disconnected at board 0. .It is evident that.

subscribers line 38 will be closed to ground atopoint stand subscriber 38 may thus signal the switchman at board A bysending current through the clearing-out shutter included in the connecting-cords. 'No matter what the mistake or fault of the operator may be, a telephoneline connected at one board with a transfer-wire cannot be left open at another board. I

It will-be seen that two spring-jackterminals will be required for each trunk or transfer wire at each intermediate board, as board O. The outside boards, A and O, are also prefe rably each provided with two spring-jack tional boards may be'readily added on either side. v

95 terminals for eachv transfer-wire, so that addidifferent groups of telephone-lines are connected,with transfer or trunk lines connecting sald boards together, the terminals of said trunk or transfer lines on the different boards being spring-jack switches, two of such terminals being provided for each transfer-wire on each intermediate board, and a ground-circuit connection for each transfer-wire, whereby a line connected at one board will be closed at the other board either to line or to the groundconneotion of the transfer-wire to which the line is connected.

In witness whereof I hereunto subscribe my name this 2d day of July, A. D. 1885.

CHARLES E. SCRIBN'ER.

WVitnesses:

GEORGE 1?. BARTON, F. H. MoOULLooH. 

